1) It looks like you did not read and/or think through my statement, as you erroneously claimed my point was "moot" while not addressing the point that I raised.
2) You presented your claim as an if-then statement pertaining to the present case we are discussing, which is the reason for the inference. However, just to clarify, there is a longer history of so-called "fact checkers" exhibiting traits. This isn't a criticism for not knowing (it's not universal knowledge), but I'm letting you know now.
3) Unfortunately, the "mistake based upon information available at the time" is not a convincing argument. The reason is that such an excuse could be used virtually all of the time to excuse the publication of misinformation. If only limited information is available at the time, then a fact checker should not make claims about the truth or falsity of stories. Quite clearly, a) limited information about the source of the virus was available months ago, b) Politifact made a particular claim about the truth/falsity of the source of the virus anyway.
Lastly, you are right that people make mistakes once in a while. However, the problem is that a) the mistake here was avoidable, b) the mistake contributed to actual harm, and c) the mistake fits a pattern of political propaganda which seeks to advance a partisan, leftist narrative under the guise of "objective" truth.